This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my applications entitled METHOD AND APPARATUS FOR CONTROLLING ON SCREEN DISPLAY AT MUTING VIDEO filed in the Korean Industrial Property Office on Jul. 2, 1997 and there duly assigned Ser. No. P97-30537 by that Office.
1. Technical Field
The present invention generally relates to a device for and method of controlling an OSD (On Screen Display) in muting video signals. More particularly, the present invention relates to a method of muting video signals without an after-image of the OSD in the state that the OSD is on when abnormal sync signals are provided to a display monitor having an OSD function.
2. Related Art
With developments in the technology of semiconductor fabrication and design, the tendency has been for electrical and electronic applications to employ microcomputers for more convenience in the use of the electronic products. For example, a microcomputer is employed in a display monitor to display data generated by a computer as visual images, and recent display monitors have an OSD function for the convenient use of the microcomputer.
Typically, the internal circuitry of a display monitor includes the following components: a control key section for generating a key signal to adjust the image on the screen; a microcomputer for generating various signals, including OSD data, blank data, and a video mute signal; a horizontal/vertical output circuit section; a video circuit section; and a power supply circuit.
In such a display unit, once the user chooses an OSD function with the control key section, the microcomputer generates OSD data according to the particular OSD function selected. As explained in more detail below, the OSD data are processed and an OSD gain signal is generated.
The OSD gain signal is boosted to a limited level by a video pre-amplifier, also contained in the display unit, and that signal is further amplified in a video main amplifier, after which the amplified signal is displayed on the screen of the display unit.
Typically, it is considered desirable to erase the display by use of a video mute function which occurs as an option when the OSD function is displayed on the screen. In order to erase the OSD on the screen, as well as to mute the video signals, the microcomputer senses a blank data signal and, under software control, the blank data is saved in a random access memory. However, such a method of erasing the OSD has problems. For example, the blank data is provided at a low transmission rate and then saved in the random access memory by means of software. This requires considerable time in erasing the OSD and, as a result, data which is partially non-deleted due to noise in erasing the OSD may be displayed on the screen of the display unit.
Therefore, there is a need for the development of a device and method which is adapted to mute the video signals without occurrence of an after-image of the OSD. Moreover, there is a need for the development of a device for and method of controlling an OSD in muting video signals using both hardware and software.
Accordingly, an objective of the present invention is to provide a device for and method of controlling an OSD in muting video signals. The device and method are adapted to mute the video signals without an after-image of the OSD by use of both hardware and software.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a device for controlling an OSD in muting video signals includes: a microcomputer for generating a cut-off signal to mute the video signals upon sensing a variation of horizontal and vertical sync signals provided thereto by a video card, and for generating blank data by executing an OSD erase control program for erasing the OSD; an OSD IC for saving the blank data in a RAM by means of an OSD erase section when variation in the horizontal and vertical sync signals provided to the microcomputer is sensed, and for generating the blank data according to an OSD control signal; and a video pre-amplifier and a video main amplifier responsive to the cut-off signal generated by the microcomputer for muting the video and for providing the blank data to a CRT to erase the OSD.
In another aspect of the present invention, a method of controlling an OSD in muting video signals includes the steps of: checking for the presence of a variation in horizontal and vertical sync signals; if there is a variation in the horizontal and vertical sync signals, muting the video signals; and erasing a RAM by generating blank data and an OSD control signal which disables the OSD.